Journal of Dental Medicine

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Statement of Problem: One of the major goals, in most dental researches, is to measure bone destruction or deposition due to the progression or regression of disease. Failure of human eyes to detect minor radiographic density changes resulted in more accurate methods such as optical densitometry and direct or indirect digital densitometry.
Purpose: The aim of this study was to determine the accuracy of a newly proposed method of indirect digital densitometry using modified Photoshop software.
Materials and Methods: Radiographs from 37 samples of urografin solution with three concentrations (12.5%, 25% and 37.5%) were taken on dental radiographic films no.2 and digitized by a scanner. A region with 800*800 pixels was cropped from each image and compressed with the Joint Photographic Experts Group (JPEG) compression algorithm and saved. These new images were then put into registration with new algorithm using MATLAB software version 6.1. This algorithm assigned each image and average pixel value (between 0 and 255). The association between concentration and calculated values for each image was tested with regression analysis and the meaning fullness of differences between calculated values was also analysis by ANOVA test. Tukey HSD and Alpha Krunbach were used whenever needs.
Results: Regression analysis revealed significant correlation between concentration and calculated average pixel value (r=0.883). The differences between average of pixels value for different concentration was significant (P=0.0001). Pixel values showed a good intra- sample and intra-group repeatability (Alpha Krunbach: a=99.96%, a=99.68%).
Conclusion: This method due to its high accuracy, easy usage and densitometer independency can be considered as a suitable alternative for conventional densitometry methods.

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Statement of Problem: Considering that the role of collagen fibers in dentin adhesion has not been thoroughly established yet, the removal of exposed collagen fibers with a deproteinization agent such as sodium hypochlorite following etching may facilitate access of adhesive resins to a substrate that is more penetrable and less sensitive to water content which in turn would lead to a more durable bonding system. Furthermore, due to sodium hypochlorite clinical application as a cleanser or canal irrigator, its effects on the surface before etching may influence adhesive bonding strength.

Purpose: The goal of this study was to evaluate the effects of a two-minute 5.25% NaOCL application on composite restorations microleakage, using two different adhesive systems.

Materials and Methods: In this interventional experimental study, on seventy-two extracted boving incisors class V cavities were prepared on dentinal surfaces. The specimens were then randomly divided into six equal groups: A1) Acid etch (AE) dentin bonding Scontchbond Multipurpose Plus (SBMBP), A2) AE/ dentin bonding One Step (OS), B1) NaOCL/ AE/SBMPp, B2) NaOCL/AE/OS, C1) AE/NaOCL/SBMPp, C2) AE/NaOCL/OS. After bonding procedures according to the manufacturer’s instructions, cavities were restored using Z100 composite. Then, the specimens were thermocycled for 500 times in water baths of 5 and 55C. After thermocycling, the specimens were immersed in a 0.2% solution of basic fuchsin for 24 hours. A buccolingual section at the center of each restoration was obtained and examined with a stereomicroscope to evaluate color penetration into cavities. The data were subjected to two-way variance analysis.

Results: The microleakage of group B was significantly less than those of A and C (P<0.001). No significant difference was found between groups A and C (P=0.73). There were also no significant differences within groups A, B and C (P=0.852). No interaction was observered between dentin bondings and surface treatment (P=0.946).

Conclusion: The findings of this study revealed that NaOCL application after etching, for hybrid layer removal, did not make any difference on microleakage as compared with conventional bonding systems. However, its application before etching improved the seal of restoration. Additionally, there was not any significant difference between two different dentin bondings.

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Statement of Problem: There are different tooth brushing methods for removing dental plaque from tooth surfaces. The effectiveness of these methods, and the time needed for instruction, learning and using seem to be different. Also, it is possible that the effectiveness of each method reduces with time, based on its difficulty level and the reduction of the patient s attention in following the given instructions. Purpose: The aim of this research was to compare the effectiveness of six different accepted tooth brushing methods on total and specific teeth, as well as on special tooth surfaces. The research also compared the time needed for instruction, learning and using the methods. Materials and Methods: The study was designed as a single blind randomised controlled trial protocol to compare the six accepted tooth brushing methods: Roll, Bass, Charters (C), Modified Stillman (MS), and Modified Bass in two ways (MB1-MB2). 15 volunteers were selected from the basic science level dental students at Tehran University of Medical Sciences. All the six methods were instructed to each volunteer, using a randomly selected sequence. Each participant should, therefore, pass six consequent courses, by the same sequences as follow: 1st Visit: After polishing the teeth, the participant was asked to abstain any kind of tooth cleaning. - 2nd visit (48-72 hours later): O Leary Plaque Index (PI) was recorded and then the randomised selected method was instructed. Then, the participant brushed his/her teeth and PI was registered again. The time needed for instruction and using the method was registered too. The participant was then asked to use this newly learned tooth brushing method twice a day for 7±1 days. - 3rd visit (7±1 days later): PI was recorded. The teeth were polished. The participant was asked to abstain any kind of tooth cleaning for 48-72 hours, as washout period of the previous method and preparation period for the next method (2nd visit of the next course). The final stage was comparing the results, in which the effectiveness of each method was evaluated based on the mean percentage of plaque reduction after the first usage, and also the mean percentage of the plaque remained after using the method for 7±1 days. The time needed for instruction, learning and using the methods were also compared. The statistical analysis was done using the SPSS software and variance analysis (randomised block design).

Results: Considering all the teeth and their total surfaces after 1st usage, the methods of C and MB1 were statistically more effective than the other methods. But the difference between these two methods was not significant. Also after 7±1 days, the differences between all methods were not statistically significant. On the posterior teeth, after 1st usage and also after 7±1 days, the method of C was significantly more effective than the others, with the exception of MB1 for which their differences were not significant. Also MB1 was significantly more effective than the methods of Bass and Roll, but only after the 1st usage. On the anterior teeth, after 1st usage, method of C was statistically more effective than the methods of Bass, MB2 and MS. Also MB1 was significantly more effective than MB2 and MS. But after 7±1 days, the differences proved insignificant. Considering the specific surfaces of the teeth on the proximal surfaces, after the 1st usage of the methods, the methods of C and MB1was significantly more effective than the others, except each other, which their difference was not significant. But after 7±1days the method of C was statistically more effective only than the methods of Bass, MB2 and MS, and the method of MB1was significantly more effective than MB2. On the buccal and lingual surfaces the differences were not statistically significant at both stage of evaluation. When statistically considering the time needed for instruction, learning and usage, the method of C needed more time than Bass and Roll methods. In the same way, MB1 needed more time than Roll method. The most time needed was related to MB2 which was more than the time needed for the methods of Bass, Roll and MS (P<0.001 and α=0.05).

Conclusion: The tooth brushing methods of Charters’ and a kind of Modified Bass method (in which Bass and Roll methods are used separately and consequently) were evaluated as the most effective methods.

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Statement of Problem: In a previous study it was reported that a durable resin-ceramic tensile bond could be obtained by an appropriate silane application without the need for HF acid etching the ceramic surface. Evaluation of the appropriate application of silane by other test methods seems to be necessary.

Purpose: The purpose of this study was to compare the interfacial fracture toughness of smooth and roughened ceramic surfaces bonded with a luting resin.

Materials and Methods: Ceramic discs of 10 mm in diameter and 2 mm in thickness were prepared. Four different surface preparations (n=10) were carried out consisting of (1) ceramic surface polished to a 1µm finish, (2) gritblasted with 50µm alumina, (3) etched with 10% HF for 2 min, and (4) gritblasted and etched. The ceramic discs were then embedded in PMMA resin. For the adhesive area, the discs were masked with Teflon tapes. A circular hole with diameter of 3 mm and chevron-shaped with a 90° angle was punched into a piece of Teflon tape. The exposed ceramic surfaces were treated by an optimised silane treatment followed by an unfilled resin and then a luting resin cylinder of 4mm in diameter and 11 mm in length was built. Specimens were stored in two different storage

conditions: (A): Distilled water at 37°C for 24 hours and (B): Distilled water at 37°C for 30 days. The interfacial fracture toughness (GIC) was measured at a cross-head speed of 1 mm/min. The mode of failure was examined under a stereo-zoom microscope and fracture surfaces were examined under Scanning Electron Microscope.

Results: The mean interfacial fracture toughness values were Group A: 1) 317.1±114.8, 2) 304.5±109.2, 3) 364.5±169.8, and 4) 379.4±127.8 J/m2±SD. Group B: 1) 255.6±134.4, 2) 648.0±185.1, 3) 629.3±182.6 and 4) 639.9 ±489.0 J/m2±SD. One way Analysis of Variance showed that there was no statistically significant difference in the mean interfacial fracture toughness for groups A1-A4 (P>0.05). However, the mean interfacial fracture toughness for group B1 was significantly different from that for groups B2, B3 and B4 (P<0.05). Independent-ٍٍٍSamples T-Test results showed that there was a significant increase in the GIC mean value for groups B2 and B3 after 30 days water storage (P<0.05). The modes of failure were predominantly interfacial or cohesive within the resin. Conclusions: The fracture toughness test method used in this study would be appropriate for analysis of the adhesive zone of resin-ceramic systems. From the results, it can be concluded that micro-mechanical retention by gritblasting the ceramic surfaces could be sufficient with no need for HF acid etching the ceramic surfaces when an appropriate silane application procedure is used.

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Statement of Problem: Craniocervical Posture is a factor in the development and function of Craniofacial Structure. Previous studies of different samples have demonstrated associations between craniocervical posture and craniofacial morphology.
Purpose: This study aimed lo examine whether any significant association is evident or not between craniocervical posture and the occurrence of Class il & Class III skeletal malocclusions.

Materials and Methods: A sample of 76 subjects with Class II & Class III skeletal malocclusion aged 9-i 1 and>18 years were selected. None of them had received orthodontic treatment. Lateral cephalometric radiographs were taken in natural head position (NHP), and craniocervical and craniohorizental angels were traced and determined for analysis of craniocervical posture.

Results: According to the craniocervical posture, most class II skeletal patients have flexed heads and class MI skeletal patients have extended heads, as a result malocclusion in these patients seems to become more severe.With increase in age. class II skeletal patients have more flexed their heads and malocclusion become more severe, while with increase in age in class ill skeletal patients, their heads become extended and once again malocclusion thought lo be more severe. In class II skeletal patients, craniocervical posture has a significant correlation with the vertical growth pattern, but shows little correlation with the horizontal growth pattern. In class 111 skeletal patients, craniocervical posture shows no correlation to any of the vertical & horizontal growth patterns, of course the mean of vertical angles is less in these patients and probably in order to make these relation significant in Class III skeletal patients there is need for more samples, in class II & class III skeletal patients, the amount of Na.prep-point A and pog-Na.prep with craniocervical posture shows a significant correlation.
Conclusion: Consideration of craniocervical posture (in addition to cephalometric angles) lead to making better treatment planning.

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Statement of Problem: Computed tomography (CT) has proved to be the most precise method to evaluate the quantity of jaw bones.In recent years, patient dose which is much more greater in CT than conventional methods has attracted more attention, and has brought the idea of using the conventional method in more accurate ways or applying new methods with lower doses.

Purpose:radiovisiography for presurgical evaluation of endosseous implants.

Materials and Methods: measured with the two aforementioned techniques. To determine the magnification factor, an acrylic stent with spherical lead markers with known diameter, has been used. Then in intra-operative phase, this distance was measured directly on the patient’s jawbone. To assess the significance of differences from radiography results and the gold standard the binomial distribution was used.

Results:significant and there was no significant difference between RVG and visual method.

Conclusion:to conventional tomography. 

Radiography is the main tool for presurgical assessment of endosseous implants.The goal of this study was the assessment of the accuracy of conventional tomography andDistance between alveolar margin and superior border of mental foramen wasFindings showed that the differences between conventional omography and visual methods wereThis study revealed that the radiovisiography method showed more precise results in comparison

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Statement of Problem: The quantity of remaining unreacted double bonds may be a significant factor pertaining to the mechanical, physical and chemical properties of restorative resins. Insufficient polymerisation within the hybrid layer may cause significant differences in the quality of this layer, and act as a reservoir for monomer release thus increasing cytotoxic potential.

Purpose: The aim of this study was to measure the degree of conversion of three generations of 3M dentin bonding agents and an experimental dentin bonding agent

Materials and Methods: The quantity was determined from the transmission IR-spectrum of the materials before and after polymerization. ScotchBond MP plus adhesive, SingleBond, Prompt L-Pop, and an experimental dentin bonding were used to measure degree of conversion. Six repetitions of each bonding were investigated. Time of light curing was 120s. Kruskal-Wallis and Mann-whitney test were used to compare groups with P<0.05 as the limit of significance.

Results: The results showed a significant difference between groups (P<0.01). A trend of increasing in Singlebond conversion obtained in comparison with ScotchBond MP plus adhesive, Prompt L-Pop and experimental dentin bonding. The degree of conversion was not statistically significant among the other dentin bondings. No significant difference was found between conversion of the experimental dentin bonding and ScotchBond MP plus adhesive (P=1.00) with P<0.05 as the limit of significance.

Conclusion: Dentin bonding technology continues to evolve toward simpler systems. However, Prompt L-Pop as a self-etching adhesive does not show the trend of increasing the degree of conversion. However, the performance of these simpler systems must be further investigated.

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Statement of Problem: Today, cross infection control is an integral part of dentistry and many dental health care workers no longer question its necessity. All dental equipments and instruments could be potentially considered as a source of infection.

Purpose: The aim of this study was the evaluation of aerobic contaminations of four disposable materials used in routine dental practice.

Materials and Methods: In this cross-sectional study, random sampling was performed and tryptone soy broth transfer culture medium was used. After 24 hours of incubation, samples were transferred to specific culture media. (Mckangy, Chocolate agar and Blood agar). Cultured bacteria were stained and studied using gram staining method. The study was carried out in a 17 weeks period.

Results: All suction tips were infected with Bacillus cereus bacterium. Two cases of cotton roll samples showed contamination with Bacillus cereus, 2 cases with gram positive, coagulase negative cocci, 1 case with Streptococcus viridians and one case with Enterobacter class A. One case of anesthetic cartridges was contaminated with Staphylococcus epidermidis and two cases with Streptococcus viridians. Two cases of gutta-percha samples were contaminated with Bacillus cereus.

Conclusion: Based of the findings of this study, the highest level of contamination was observed in saliva ejector tips. Contamination with Bacillus cereus was seen more frequently.

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Background and Aim: A strong causal relationship exists between cigarette smoking and development of oral squamous cell carcinoma, so oral screening using exfoliative cytology has been recommended to facilitate the early diagnosis of cellular alterations in oral mucosa and silver staining (AgNOR technique) has been proven to be of value in the detection of incipient cellular alterations. The purpose of this study was to compare the argyrophilic nucleolar regions (AgNORs) count of cells collected from normal mucosa of cigarette smokers with that obtained from non- smokers.

Materials and Methods: In this cross-sectional study, cytologic smears of normal tongue, buccal mucosa and floor of the mouth from 19 smokers and 19 non- smokers were stained for AgNORs. The AgNORs count was established on 100 cells. The count value of groups were compared and analyzed using the Levens, Paired T, Student and Factorial tests. Using P<0.05 as the limit of significance.

Results: The AgNORs were round and had a clustered distribution in both groups. The mean AgNORs count was statistically higher in cells of smokers than non- smokers (P<0.05). There was a significant difference between smears from the floor of the mouth and other anatomical sites in both groups. In this study, no correlation was found between AgNORs count and gender.

Conclusion: Analysis of AgNORs suggests that there might be a correlation between the smoking habit and an increased rate of cellular proliferation in the oral mucosal cells.

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Background and Aim: Chlorhexidine is a mouthwash with known antibacterial effect but its antifungal effect is not clear. The aim of this study was to compare the antimicrobial effects of nystatin and chlorhexidine mouthwashes (one Iranian product and the other, commercial) on Candida albicans under in vitro condition. Materials and Methods: In this experimental study, the strains of Candida albicans used consisted of one standard strain (PTCC 5027) and ten local isolates. The latter were obtained from patients referred to different dental clinics in Kerman city. The specimens were taken from the gum and palate area by sterile swabs and dipped into Stewards transport medium, transferred to the laboratory within one hour, and cultured on Sabauraud dextrose Agar. Colonies showing the characteristic appearance of Candida were further cultured and routine differential tests including germ tube formation were performed to confirm the diagnosis of

C.albicans. These were used to prepare a microbial cell suspension of 0.5 Mc Farland concentration. Each cell suspension was inoculated over duplicate plates of SDA and 4 wells of 5 mm diameter were made using sterile cork borers. Each previously coded mouthwash was placed in corresponding well and incubated for 24-48 hours and the diameter of inhibition zone was measured with ruler. The minimum inhibitory concentration (MIC) of each mouthwash for each isolate of Candida albicans was determined using dilution tube technique. Data were analyzed by SPSS package using proper statistical tests with P<0.05 as the limit of significance.

Results: There was a significant difference between the antimicrobial effects of the four tested mouthwashes. The results indicated that Iranian nystatin mouthwash had the greatest effect and the average inhibition zone from the highest to the lowest was associated with Iranian nystatin, foreign nystatin, Iranian chlorhexidine and foreign chlorhexidine respectively. The MIC determination revealed that generally nystatin was more effective than chlorhexidine. No statistical difference was seen between the Iranian and foreign samples.

Conclusions: Despite the antifungal effects of chlorhexidine, more investigations on different strains of C.albicans is required before recommending its cilinical application.

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Background and Aim: Maintaining the original canal path and safety of canal preparation during instrumentation in curved canals have been subjected to many challenges. The aim of this study was to compare several parameters of root canal preparation using flexmaster rotary and hand used Nickel-Titanium instruments.

Materials and Methods: In this experimental study, sixty extracted human teeth with root canal curvatures between 10 and 42 degress were devided into two similar groups with equal mean curvatures. Root canals in one group were prepared using flexmaster rotary instruments and the other with NiTi hand files.After canal preparation, different parameters such as straightening of curved root canal, loss of working length, fracture rate, perforation and working time, were evaluated and compared between the two groups. Data were analyzed by t student test with p<0.05 as the limit of significance.

Results: Results showed that both instruments maintained the original canals' curvature. No loss of working length, instruments fracture or perforation was recorded. Working time was significantly shorter for flexmaster than hand files.

Conclusion: Both systems under investigation respected original root canal curvature and were safe to use. Therefore the rotary techniques could be successfully introduced to undergraduate endodontic programmes.

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Background and Aim: Lead is one of the most dangerous metallic poisons which can lead to acute and chronic poisoning with a broad range of systemic and oral signs. The aim of this study was to evaluate the relationship between the prevalence of oral complications and blood lead level in workers employed in Koushk lead mines, Yazd province.

Materials and Methods: This analytical study was conducted on 70 subjects employed in Koushk lead mines and 70 workers in Yazdbaf textile factory as control group. A questionnaire including demographic information and medical questions was completed for each case and oral manifestations were recorded, as well. Blood samples were taken from subjects and blood lead level was measured by atomic absorption spectrophotometer. Data were analyzed using t, Chi-Square and Mann Whitney tests with p<0.05 as the limit of significance.

Results: The mean lead level was 7.06 µg/dl in case group and 4.97µg/dl in control group (P= 0.039). In case group, 3 subjects had blood lead level more than 20µg/dl. Statistical analysis showed significant differences regarding neurologic disorder, chronic fatigue, existence of lead line, mucous pigmentation, gingivitis, tongue burning, taste sense reduction and DMF between case and control groups (P<0.05).

Conclusion: Based on the results of this study, since the mean blood lead level in mine workers was in normal limits, the observed symptoms were not related to systemic poisoning. Direct contact of the oral mucosa with the lead in breathing air or other factors related to overall health problems in mine workers may be responsible for the present findings. Further studies are recommended on similar subjects working in different conditions.

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Background and Aim: Iranian temporary cement, Tem Band, has been manufactured by Golchai company, and introduced to market as a suitable material but its properties have not been tested yet. The aim of this study was to investigate the setting time, film thickness, compressive strength, disintegration and arsenic content of Tem Band and Temp bond temporary cements and compare them to ISO 3107. Materials and Methods: In this experimental study, 12 samples from each cement were obtained and setting time, film thickness, compressive strength, solubility and disintegration were tested according to ISO 3107. In addition, arsenic content was tested based on ASTM 6052. Data were analyzed with t-test and p<0.05 was considered as the limit of significance.

Results: The average setting time of Tem Band was 5 minutes and 47 seconds (4.17 minutes for Temp Bond), the average film thickness was 6.67 micrometer for Tem Band and 4.08 micrometer for Temp Bond. There was no difference between two cements regarding setting time and film thickness and for both was at the standard range. Compressive strength of Tem Band was 5.67 MPa and 8.5 MPa for Temp Bond. The difference was statistically significant but for both cements was less than standard (35 MPa). There was no significant difference regarding the solubility and disintegration tests. In both samples, the solubility and disintegration values were in standard ranges. Both cements did not contain arsenic but lead level was at the maximum standard range in Tem Band.

Conclusion: Considering these results, both cements are applicable to different clinical situations based on their physical properties. Studies on the biocompatibility of the Iranian cement is recommended.

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Background and Aim: Sufficient polymerization is a critical factor to obtain optimum physical properties and clinical efficacy of resin restorations. The aim of this study was to evaluate wear rates of composite resins polymerized by two different systems Light Emitting Diodes (LED) to and Halogen lamps.

Materials and Methods: In this laboratory study, 20 specimens of A3 Tetric Ceram composite were placed in brass molds of 2*10*10 mm dimensions and cured for 40 seconds with 1 mm distance from surface. 10 specimens were cured with LED and the other 10 were cured with Halogen unit. A device with the ability to apply force was developed in order to test the wear of composites. After storage in distilled water for 10 days, the specimens were placed in the wear testing machine. A chrome cobalt stylus with 1.12 mm diameter was applied against the specimens surfaces with a load of 2 kg. The weight of each samples before and after 5000, 10000, 20000, 40000, 80000 and 120000 cycles was measured using an electronic balance with precision of 10-4 grams. Data were analyzed using t test and paired t test. P<0.05 was considered as the limit of significance.

Results: Mean weight in both groups had statistically significant difference before and after all cycles (P<0.05). In halogen group 5000 and 10000 cycles led to significant difference with 40000, 80000 & 120000 cycles (P<0.05). In LED group 20000 cycles had significant difference with both 5000 and 120000 cycles (P>0.05).

Conclusion: Based on the results of this study, LED and halogen light curing units resulted in a similar wear rate in composite resin restorations.

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Background and Aim: Use of provisional restorations is one of the important phases in the treatment of patients who need fixed prosthesis. Some physical properties are required for these materials. The purpose of this study was the comparison of some physical properties of 4 kinds of resins: Trim, Tempron, Duralay (Aria Dent) and Acropars TRII.

Materials and Methods: In this experimental study, transverse-strength (TS), setting time (ST), polymerization shrinkage (PS) and temperature rise (TR) during polymerization were tested. In transverse strength test, 5 samples of each resin were made. TS testing was done with an Instron testing machine. ST testing (5 samples in each group) was done with Gilmore needle. In PS test, 11 cylindric samples were prepared from each resin and the shrinkage was examined with digital micrometer (up to 24 hours). In TR test, after mixing the powder and liquid of resins (8 samples in each group), the temperature rise was recorded with 10 seconds interval (up to 15 minutes). Data were analyzed with one-way ANOVA and Tukey HSD tests with p<0.05 as the limit of significance.

Results: In TS test, all samples of Trim were bent and no fracture was observed, while Tempron and Duralay showed no significant difference. Both Tempron and Duralay revealed high significant difference with Acropars TRII (P <0.01). In ST test, the difference between groups was significant (P<0.01). The lowest ST was observed in Acropars TRII (7 min), and the highest in Tempron (9.53 min). In PS test, significant difference was observed between Trim and Acropars TRII (P<0.01). PS was completed after 120 min in Tempron and Trim groups. However, PS continued to increase in other groups. In TR test, the difference between groups was significant (P<0.05). Duralay showed the highest TR and the lowest was seen in Trim.

Conclusion: In this study, Trim showed better properties than other studied groups. Acropars TRII had the lowest strength. The highest temperature rise was recorded for Duralay and Tempron, respectively.

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Background and Aim: Although toothbrushing is still the most effective method in plaque reduction, it is insufficient for total plaque removal. Considering this limitation, it is suggested that toothbrushing could be aided by chemical methods. For this purpose, it is advised to use some kind of mouthrinses before toothbrushing to increase the rate of microbial plaque removal. Several prebrushing mouthrinses are available in the market and comparing their efficiency is valuable for dentists. The aim of this study was to investigate and compare the effect of two prebrushing mouthrinses, Plax and Irsha, on dental plaque reduction.

Materials and Methods: This clinical trial was carried out as an interventional and triple blind protocol, using completely random block design. For this purpose, questionnaire and initial examination chart was filled for 50 healthy volunteers between the age of 18 and 40 years and finally 30 individuals were selected based on the inclusion/exclusion criteria. If scaling and polishing was necessary, it was performed at least 2 weeks before starting the main program. Then, each volunteer participated in a 4 steps program, including one step toothbrushing without use of mouthrinse and three steps toothbrushing after use of one of the mouthrinses (Plax, Irsha, Placebo). Data were analyzed by SPSS software using factorial analysis, ANOVA and Tukey’s multiple comparison tests with p<0.05 as the limit of significance.

Results: Toothbrushing without use of mouthrinse decreased the amount of plaque, significantly (P<0.0001). Use of mouthrinse without toothbrushing decreased the amount of plaque significantly (P<0.0001). The amount of plaque reduction after use of various mouthrinses (Plax, Irsha, Placebo) showed no statistical differences (P=0.761). Use of the mouthrinses before toothbrushing, had no statistically significant effect on the final results after toothbrushing (P=0.331).

Conclusion: According to the findings of the present study, although using mouthrinses decrease the amount of dental plaque significantly, but the prebrushing mouthrinse didn't show statistically significant effect on final result after toothbrushing.

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Background and Aim: Low birth weight is a significant public health issue. Recent studies have suggested periodontal diseases as risk factor for preterm labor. The aim of this study was to assess the relation between gingival health and preterm labor in a sample of Iranian female population.
Materials and Methods: In this cross sectional study, 201 pregnant women without any systemic diseases or other risk factors like psychotic conditions were selected. Ninety-nine of them had term labor (infant≥37 weeks) and 102 had preterm labor (infant<37 weeks). Bleeding index, pocket depth and debris index were measured. Data were analyzed by Chi-square and Mann-Whitney tests with p<0.05 as the level of significance.
Results: Bleeding index, probing depth and debris index showed statistically significant differences between preterm and term labor mothers (P<0.001).
Conclusion: According to the findings of this study, there is a significant relationship between gingival health and duration of pregnancy. Consequently, periodontal diseases could be risk factor for preterm labor. Oral hygiene is strongly recommended to be included in pregnancy health programs.

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Background and Aim: Mechanical preparation of canal is one of the most important stages in root canal therapy. Various kinds of hand or rotary techniques are used for mechanical preparation of canal and each of them has advantages and disadvantages. During canal preparation, extrusion of debris from the apical foramen can result in periapical inflammation and increased pain and edema. The aim of this study was to compare hand instrumentation technique with three rotary systems (Profile, Race, Flex Master) regarding the amount of extruded debris from apical foramen during canal preparation.

Materials and Methods: In this experimental in vitro study, one hundred human extracted single rooted mandibular premolars with curvature between 0-10 degrees were selected and divided into four groups of 25 teeth each. All teeth were shortened to 15 mm length by cutting the crown. Group H was prepared by hand step back technique, group P by Profile system, group R by Race system and group F by Flex Master system. For debris collection, vials containing distilled water were used which were weighed before preparation. After the end of canal preparation, vials were completely dried and weighed again. The difference between weights of vials in two stages was the weight of debris extruded from apical foramen. The groups were compared by One-way ANOVA with p<0.05 as the level of significance.

Results: Group H had the highest mean weight of debris which showed significant difference with all three rotary groups (P<0.001). The lowest mean weight of debris was observed in group R (Race) which was significantly different from group F (Flex Master) but not significantly different from group P (Profile).

Conclusion: Based on the results of this study, race rotary system caused less debris extrusion from apical foramen compared to hand step back technique and Flex Master rotary system.

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Background and Aim: Mineral Trioxide Aggregate (MTA) is a material used in many endodontic problems. Recently a number of studies, have reported that Portland Cement (PC) and MTA have similar physical, chemical and biologic properties. In addition, a material known as Root MTA which is produced in Iran has been claimed to have similar properties to Pro Root MTA. If these claims are true, possible use of PC and Root MTA in clinic instead of Pro Root MTA will be quite cost effective. The aim of this study was to investigate the toxicity of Pro Root MTA, Root MTA and Portland Cement on L929 mouse fibroblasts.

Materials and Methods: In this experimental study 0, 4, 24 hours and 7 days' extracts of materials were transferred to cell culture plates containing L929 fibroblasts. After 24 hours incubation, cells were stained by Neutral Red (NR), and optical density (OD) of each cell was read with ELISA reader. Data were analyzed using Tukey HSD and one way analysis of variance. P<0.05 was considered as the level of significance.

Results: In all surveyed groups and negative control group, at all time points separated cells from the base of the well were round. Refraction which is a characteristic of cellular death was not observed, whereas the separated cells from the base of well in positive control group showed refractional characteristic.

Conclusion: Based on the findings of this study Pro Root MTA, PC and Root MTA have the same biocompatibility. PC seems to have the potential to be used in the same clinical situation as MTA. However in order to replace MTA with these less expensive materials more in vitro and in vivo studies are suggested.

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Background and Aim: Incomplete root development caused by trauma ,caries, or pulpal pathosis requires special attention and treatment . Although calcium hydroxide apexification has been used successfully for years but it requires patient cooperation and multiple appointments . Single visit apexification with MTA has been used in recent years. The purpose of this study was to compare bacterial microleakage of two types of MTA (Made in Iran and Brazil) applied as apical barrier in open apex teeth.

Materials and Methods: 48 single root teeth were used in this experimental in vitro study. Teeth apices were prepared as open apex teeth. For canal obturation the 4mm of root end was filled with 2 types of MTA (white Iranian MTA salami co. Iran and Angelus MTA Angelus Brazil) from coronal access. Teeth were mounted in self-cured acryl and put in BHI microbial culture. A suspension of Staphylococcus epidermidis was injected from coronal area into the root canals.The teeth were incubated and examined every 24 hours for microbial microleakage, indicated as turbidity in culture. Data were analyzed using Fisher exact test with p<0.05 as the level of significance.

Results: Microleakage appeared after 15 days in all Iranian and after 17 days in Angelus MTA samples.There was no significant difference between microleakage of two types of MTA (P = 0.48).

Conclusion: Based on the results of this study, there was no significant difference between microleakage of Iranian and Angelus MTA. If further studies confirm other physical, chemical, biological and sealing properties of Iranian MTA, it could be recommended for clinical application